Rocky Habitat

Introduction

The very irregular typography of the relieves in the Canary Islands favours the development of a community living on rocks or in their slits. These communities are characterised by a large number of endemic plants, sometimes observable in extremely restricted areas. The typical species associated with these coenosis belong to the genera Aeonium and Grenowia, who in turn belong to the family of Crassulaceae. Their appearance is that of small shrubs or perennial herbs often with succulent leaves held in basal rosettes. Such rosettes take root on the perpendicular rocky areas and persist all the year. When the rosette is perfect, some floral scapes (sometimes very long and narrow) branch off and hang from the wall. These communities can be observed both on natural rocks and on artificial structures, especially walls, provided they are not made of concrete.

In the northern part of Tenerife, on the humid and shadowy slopes of the Anaga massif and inside the range of the forests of trees with laurel-like leaves we can observe a coenosis characterised by Aeonium cuneatum an endemic plant living only in Tenerife, A. ciliatum and Aichrysum laxum. In the hotter and less humid microclimate we can find Aeonium haworthii, A. urbicum, Sonchus acaulis and S. congestus.

In the Teno massif there are very humid ravines influenced by the sea winds. There Vieraea Iaevigata, Crambe scaberrima and Cheirolophus canariensis give birth to communities that depend on or tolerate the sea aerosol. Such communities may get in touch with the coenosis of Euphorbia aphylIa., while in the artificial ruins such as walls or roofs we can often observe species like Antirrhinum majus or Centranthus ruber.

Aegnium Cuneatum

(Crassulaceae) Bejeque

The genus Aeonium consists of more than 30 species most of which can be observed in the Macaronesia Islands, with some representative also in Morocco and Yemen. It consists of perennial herbs, with an igneous basal part and succulent leaves, generally wedge-shaped, held in a base rosette and in a few cases along the trunk. The small flowers are arranged in inflorescences sometimes very large, upright and pyramidal. A. cuneatum has a very short upright trunk and it almost always has runners. The base rosette is up to 50 centimeters wide and it consists of hairless sea-green, light blue leaves. The light yellow flowers are grouped in a cone-shaped inflorescences, up to one meter long which, at the base, are 30 centimetres wide. It is an endemic species of Tenerife.

Aegnium Ciliatum

It differs from Aeon jum cuneatum because it has a larger igneous base with more branches. The deep green rosettes are smaller (never more than 20 centimetres in diameter) and often have reddish margins. The flowers may be white-green or slightly pinkish. The inflorescence is pyramidal, much branched, but smaller. It can only be observed in Tenerife and La Palma.

Aichrysum Laxum

It is an upright grass which may be annual or biennial and slightly comose. The trunk is up to 30 centimeters high, with more or less upright branches. The almost rhomboidal fleshy leaves are woolly-comose. The yellow flowers are sparse inflorescences and they are far from one another. It is an endemic species of Canary Islands, but it cannot be observed in Lanzarote or Fuertenventura.

Sonchus Acaulis

It is a perennial grass with igneous base. Its leaves are held in a basal rosette of great dimensions and it can reach one meter in diameter. The tomentous pinnate leaves have a pointed apex. The floral scape is up to one meter and half high and carries, on the upper part, some flower-heads characterised by the involucre white-tomentous bracts. It is an endemic species of the Canary Islands.

Aegnium Haworthii

The A. haworthii is characterised by rosettes not larger than 11 centimeters. The pale pink or white flowers have rosy markings. In this case, the inflorescence is round-shaped and its diameter is not larger than 20 centimeters. It is an endemic species of Tenerife.

Sonchus Radicatus

It differs from the previous Sonchus for the generally larger flower-heads, which are smaller in quantity and with less tomentum. It is an endemic species of Tenerife.

Vieraea Laevigata

It only can be observed on the basalt cliffs overlooking the road near the Fraele rocks, next to the Teno Massif, in the north-west area of the Island of Tenerife. Vieraea laevigata is a shrub living on rocks; it can be recognised by its flowers which are grouped in yellow flower-heads. The trunk is greyish. The ovate-lanceolate leaves have a serrated margin, especially on the upper part. In spring it is in bloom and it brightens up the dark grey typical of the basalt rocks cheering up the landscape of this already beautiful area. It is a very rare species and the opening of other roads, plus the building of some canals for water collection are unfortunately further reducing the population.

Crambe Scaberrima

It is a shrub not higher than one meter and half. The ovate leaves are very rough and slightly dentate on the margin; they have a very short petiole, divided into two wings. The small white flowers are grouped in inflorescences. It is an endemic species of Tenerife, where it is plentiful especially on the Teno area. There we can also find Crambe laevigata an endemic plant restricted to this area only and in danger of becoming extinct. This differs from Crambe scaberrima because of the smooth leaves and the smaller dimensions.

Cheirolophus Canariensis

This rare plant is endemic to Tenerife. We can observe it along the high rocky cliffs at Fraele, near Cape Bellavista. It is a species living on the basaltic cliffs where it catches the eye thanks to its light mauve flower-head. The leaves of this "fleurde-lis" are pinnate-lobate and as sometimes the lobes are very deep the leaves may look whole.

Antirrhinum Majus

It is certainly the most common species among all those of the genus Anthirrinum and it has been cultivated for many centuries in the gardens all over the world. The "snapdragon" is a perennial grass, up to 75 centimeters high and likes most sunny and rocky places, especially in the slopes or dry-stone walls. The flowers are up to five centimeters large and have very intense and variegated colours, varying from white to yellow, with markings from purple to deep purple. There are many cultivators of A. majus both for the dimensions of the scape and for the many-colours of the flowers.

Centranthus Ruber

This plant is often associated with the snapdragon with which it shares a preference for the dry-stone walls which can be found in the country or in the rocky gardens in the cities. The "red valerian" has trunks of up to 80 centimeters high, generally branched, with opposite glaucous leaves. The purple or reddish flowers are small and grouped in umbelliform inflorescences. The leaves and the inflorescences give Centranthus ruber a very decorative appearance. It is a typical species of the regions around the Mediterranean, from Asia Minor to Morocco.